Recent finding from this laboratory suggested that EGF plays a role during androgen-induced fetal reproductive tract development. We propose to investigate its role further by testing: 1. whether Western blot positive different EGF-immunoactive protein molecules present in the fetal male reproductive tract, are modulated in response to testosterone-induced male reproductive tract differentiation; 2. whether EGF-mRNA synthesis is induced in response to this differentiation and whether testosterone plays a role in the induction ; 3. whether in situ hybridization of the developing reproductive duct detects a cell type producing increased expression of EGF-mRNA in response to this differentiation; 4. whether EGF receptor plays a role by determining the effect of the anti-EGF receptor antibody in organ culture assay of the differentiation and by determining its expression using Western blot and immunohistological analysis during the Wolffian duct differentiation; 5. whether EGF receptor-mRNA synthesis is modulated during the male reproductive differentiation and whether testosterone plays a role in this induction.